Page - 31 - in Biodiversity and Health in the Face of Climate Change

31 • Health effects of milder winters Cold weather events are well known to be associated with excess mortality and morbidity (European Environment Agency 2017). For example, all of the UK’s devolved nations report increases in all-cause mortality with reducing temperatures below health-related baselines, though mortality tends to be due to secondary impacts on the cardiovascular and respiratory systems rather than due to hyperther- mia (Hajat 2017). As with high temperature events, factors other than temperature are also important, including building insulation, the availability, efficiency and cost of heating and social factors, such as awareness, all of which vary spatially (Robinson et  al. 2018). By extension, milder winters do not necessarily result in a reduction in cold weather impacts. Nevertheless, all other things being equal milder winters should have health benefits in view of warmer mean temperatures (fewer Heating Degree Days) and fewer extreme cold-weather events (European Environment Agency 2017). Incidence rates and timings of influenza and other infectious diseases are linked to climatic drivers, therefore there are likely to be secondary effects. Although changes have been observed in influenza peaks and seasons, climatic and other determinants are currently uncertain (Caini et  al. 2018). • Outdoor air quality Like other impact groups, air quality is also greatly influenced by factors other than climate change, with changes in emissions being particularly important over short time horizons. For example, regional haze in South East Asia is ultimately caused by biomass burning, though exacerbated by other climate-related factors. Even far from initial sources, haze has been linked with multiple impacts on physi- cal health, including through the respiratory and cardiovascular systems due to the predominance of fine particulate matter (<2.5  μm) as well as impacts on agriculture and tourism (Latif et  al. 2018). Despite the influence of other factors, studies sug- gest that over the longer term there are likely to be climate penalties associated with a number of air pollutants known to impact both human and ecosystem health e.g. ozone and particulate matter (though with considerable uncertainty). Dust storms are more directly associated with climatic factors and changes in wind and precipi- tation are likely to affect the distribution and extent of associated health burdens, including respiratory, cardiovascular and infectious diseases (Schweitzer et  al. 2018). Alongside more gradual changes to baseline air quality affecting annual average concentrations and chronic human health effects, climate change therefore also has a role in determining the frequency and severity of meteorological condi- tions that give rise to episodes of poor air quality. Air quality episodes with elevated concentrations of air pollutants can lead to a range of chronic and acute diseases, evidenced by health outcomes that include increased hospital admissions and excess morbidity and mortality rates. The stagnation events associated with air quality epi- sodes can also be associated with summer heat waves and therefore have cumulative outcomes for human health (Doherty et  al. 2017). 2 Biodiversity, Physical Health and  Climate Change: A  Synthesis of  Recent Evidence